Method for adjusting the angular travel of a wiper mechanism by modifying the length of a crank and crank comprising a deformable section

ABSTRACT

The invention concerns a method for adjusting the angular travel of a motor vehicle wiper mechanism, comprising a connecting rod and a crank, wherein the crank includes a body which extends longitudinally in a substantially horizontal plane, which is articulated at one first end about a vertical axis (A), and which is articulated at a second end to the connecting rod, comprising a step which consists in adjusting the angular travel by modifying the distance between the first and the second articulated ends of the crank. The invention is characterized in that the adjusting step consists in modifying the length of a longitudinal section of the body of the crank.

The invention proposes a method of adjusting the angular travel of amotor vehicle wiping mechanism, of the type comprising a link and acrank, of the type in which the crank comprises a body which extendslongitudinally in a substantially horizontal plane, which is articulatedat a first end about a vertical axis, which is articulated at a secondend on the link, of the type comprising a step of adjusting the angulartravel by modifying the distance between the first and secondarticulated ends of the crank.

Such articulations with link or links and crank or cranks are found forexample in driving devices in which an electric motor, possiblyassociated with a gearbox, drives in alternating sweep at least onewiper fixed to a drive shaft which is mounted for rotation with respectto the vehicle.

By means of a link and crank mechanism, it is for example possible toconvert a continuous rotary movement of the output shaft of the drivemotor into an alternating rotary movement of the drive shaft of eachwiper.

The geometry and kinematics of this mechanism, and in particular thelength of the cranks, determine the angular travel of each wiper. Bymodifying this geometry, it is possible to obtain, from one and the sameoutput movement of the motor output shaft, two different angular travelsfor each of the two wipers.

It is therefore clear that it is particularly important to be able tocorrectly control the geometry of the mechanism and in particular thelength of the links and cranks which are articulated between them bymeans of swivel articulations, but also the positioning of the variouselements with respect to each other.

However, from one mechanism to another, it may happen that scatteringsarise in the various characteristic dimensions of the mechanism and thatunsatisfactory angular travels of the wiper result therefrom.

Thus it has already been proposed, in particular in the documentEP-A-0,904,997, to be able to “vary” the length of a crank of such amechanism by adjusting the position of the swivel of the swivelarticulation on this crank.

For this purpose, the swivel is fixed through an oblong hole, forming anadjustment aperture, and its length is determined by clamping onmounting, the length over time thus being linked to the reliability ofthe clamping system.

It has also been proposed in the document U.S. Pat. Nos. 5,619,886 and5,070,572 to be able to adjust the position of the swivel by means of anintermediate adjustment piece which is able to move in an adjustablemanner about a vertical axis. The swivel is mounted on this intermediatepiece so that the axis of the swivel is off centre with respect to thevertical axis of the intermediate piece. Adjustment of the position ofthe swivel is thus obtained by modifying the angular position of theintermediate piece.

However, it became clear that the various devices proposed up to thepresent time were either too complex to produce or insufficientlyreliable with regard to the maintenance over time of the exact positionof the swivel on the crank in its oblong hole.

Thus the object of the invention is to propose a simple and reliableadjustment method which guarantees a precise position of the swivel overtime despite the forces transmitted and the vibration suffered by themechanism over time.

For this purpose, the invention proposes a method of the type describedabove, characterised in that the adjustment step consists of modifyingthe length of a longitudinal portion of the body of the crank.

According to other characteristics of the invention:

the adjustment step consists of permanently deforming at least part ofthe longitudinal portion of the crank body;

the adjustment step consists of reducing the length of the portion ofthe crank body by bringing together the articulated ends of the crankbody in a longitudinal direction;

the adjustment step is performed after a step of mounting the wipermechanism on a test bench.

The invention also proposes a crank belonging to a movement transmissionlinkage of a motor vehicle wiper mechanism, of the type comprising abody which extends longitudinally in a horizontal plane and whichcomprises a first longitudinal end articulated on a link of the linkage,and a second longitudinal end which is connected to a wiper arm andwhich is articulated about a vertical axis, of the type in which thedistance between the two articulated ends of the crank is adjustable,characterised in that the body of the crank comprises at least oneportion which is able to be deformed permanently in order to modify andadjust the distance between the two articulated ends of the crank.

According to other characteristics of the invention:

the said portion of the crank body comprises at least one oblong hole ofgeneral longitudinal orientation which delimits two opposite deformablelongitudinal branches.

Other characteristics and advantages of the invention will emerge from areading of the following detailed description, for an understanding ofwhich reference will be made to the accompanying figures, amongst which:

FIG. 1 is a schematic representation in perspective of a conventionalwiper mechanism comprising a mechanism or linkage for driving andmovement transmission of the link and crank type;

FIG. 2 a is a schematic representation to a larger scale of a crank ofthe wiper mechanism depicted in FIG. 2 a, in accordance with theinvention and as it is before the adjustment of the angular travelaccording to the invention;

FIGS. 2 b and 2 c are views similar to that in FIG. 2 a in which thecrank is depicted after its deformation for adjusting the sweep angle.

For the description of the invention, the orientations vertical,longitudinal and transverse will be adopted non-limitingly according tothe reference frame V, L, T indicated in FIG. 2 a.

In the following description, identical, similar or analogous elementswill be designated by the same reference numbers.

FIG. 1 depicts a conventional wiper mechanism 20 of a motor vehiclewindscreen (not shown) which comprises two wiper blades 22. Each bladeis able to move in rotation about a substantially vertical axis A. Thewiper mechanism 20 comprises a linkage composed of links 24 and cranks26 which connect the blades 22 to a geared motor unit 28 which drivesthe wiper mechanism 20.

In a known manner, and as depicted in FIGS. 2 a to 2 c, each crank 26comprises a roughly flat body 30 which extends longitudinally in ahorizontal plane and which is articulated, at a first end 30 a, aboutthe vertical rotation axis of the associated blade 22.

The body 30 comprises, at its second free end 30 b, an articulationswivel 32 for the crank 26 with a link 24.

Each wiper blade 22 is for example intended to be mounted at the top end34 of a drive shaft 36 so as to be driven in an alternating rotary sweepmovement about the axis A of the shaft 36. The shaft 36 is guided in abearing body 38 (depicted in FIG. 1) which is intended to be arrangedclose to the window to be wiped, on the internal side of a bodyworkelement or vehicle structure (not shown) through which only the top end34 of the shaft 36 projects.

In order to provide the rotational driving of the wiper blade 22 aboutits axis A, and as depicted in FIGS. 2 a, 2 b and 2 c, the drive shaft36 extends vertically upwards from the first end 30 a of the body 30 ofthe crank 26.

In accordance with the teachings of the invention, and as depicted inFIG. 2 a, the body 30 of the crank 26 comprises at least one portion 40which is able to be deformed permanently so that it is possible toadjust the distance “D” between the two ends 30 a, 30 b of the body 30of the crank 26, with a view to modifying the angular travel “α” of theblade 22.

For this purpose, the portion 40 of the body 30 preferably comprises acentral oblong hole 42 of longitudinal orientation overall, whichdelimits two longitudinal branches 44. According to a preferredembodiment of the invention, the oblong hole 42 is positioned and sizedso that the branches 44 are symmetrical with respect to the medianlongitudinal axis of the crank 26.

The dimensions of the oblong hole 42 and of the portion 40 are such thatthe longitudinal branches 44 can be deformed for adjusting the distancebetween the two ends 30 a, 30 b of the body 30 of the crank 26. However,they must not deform during the functioning of the wiper mechanism 20.

The invention also proposes a method of adjusting the angular travel “α”of each blade 22 of the wiper mechanism 20. For this purpose, the wipermechanism 20 is first of all mounted on a test bench which makes itpossible in particular to determine the differences between the angulartravel “α” of each blade 22 and the actual angular travel “α”. Fromthese values, it is then possible to adjust the wiper mechanism in orderto have an optimum angular travel “α”.

The adjustment step is performed whilst the crank 26 is mounted on thewiper mechanism 20, which makes it possible to eliminate the steps ofremoval and then refitting of each crank 26, and therefore to reduce thetime for mounting the wiper mechanism 20.

The angular travel “α” of the blade 22 depends on the dimensions of thelinks 34 and the cranks 30 of the linkage, as well as of the gearedmotor 36. However, only one modification of the dimensions of the crank26 makes it possible to vary the angular travel “α” of the blade 22independently of the other blade 22.

The angular travel “α” of the blade 22 depends on the length of thecrank 26, and the variation in the angular travel “α” is inverselyproportional to the variation in the length of the body of the crank.Thus, for example, a small angular travel “α” corresponds to a longcrank length 26 and, conversely, a large angular travel “α” correspondsto a short crank length 26.

Thus, if the angular travel “α” of the blade 22 in question is toosmall, this means that the distance between the ends 30 a, 30 b and thebody 20 of the associated crank 26 is too great.

To adjust the angular travel “α” of the blade 26, the adjustment methodincludes a step of adjusting the angular travel “α” of the blade 22which consists of varying the length of the longitudinal portion 40 ofthe body 30 of the crank 26.

Since the portion 40 is able to be deformed because of the presence ofthe oblong hole 42, the adjustment of the angular travel “α” of theblade 22 consists of deforming the portion 40, that is to say thebranches 44. Moreover, the branches 44 are deformed permanently so thatthe crank 26 next definitively keeps the adjustment for its normalfunctioning.

In order to increase the angular travel “α”, the distance between thetwo ends 30 a, 30 b is reduced. For this purpose, and as depicted inFIGS. 2 b and 2 c, the branches 44 are deformed symmetrically withrespect to the median longitudinal axis of the body 30 of the crank 26.

This deformation can consist of a bringing together of the branches 44,as depicted in FIG. 2 b, or a separation of the branches 44, as depictedin FIG. 2 c. In all cases, the deformation is performed by means of atool adapted to the required deformation mode and to the nature of thebody 30 of the crank 26.

The tool is for example in the form of a clamp, each jaw of whichcooperates with a branch 44 of the crank 26 in order to separate it fromor bring it closer to the other branch 44. In addition, in order toavoid creating a stress concentration zone at the deformation producedby the jaws of the tool, the latter preferably have a rounded shape.

The deformation consists of deforming the branches 44, but not modifyingthe length thereof. As a result the ends 30 a, 30 b of the body 30 ofthe crank 26 are overall brought together longitudinally.

The deformation of the portion 40 can consist, as depicted in FIG. 2 b,of bringing together at least part of the branches 44 so that theyoccupy a part of the volume of the defined by the oblong hole 42. Thebody 30 of the crank 26 then occupies a reduced volume. However, theamplitude of adjustment of the angular travel “α” is limited by thevolume defined by the oblong hole 42.

The deformation of the portion 40 can thus consist, as depicted in FIG.2 c, of separating transversely and at least partly the branches 44which then extend transversely beyond the original external longitudinaledge of the body, whose transverse dimension is thereby increased.However, the amplitude of adjustment of the angular travel “α” isgreater than the amplitude of the adjustment consisting of bringingtogether the branches 44, and this amplitude is limited to the length ofthe oblong hole 42.

By way of variant of the invention, the length of the body of the crankcan be increased by applying the method described above. For thispurpose, in its initial state, that is to say before its deformation,the crank 26 is in the form depicted in FIG. 2 c in which the branches44 are partly separated.

Thus, in order to increase the length of the body 30 of the crank 26 andtherefore to reduce the angular travel “α” of the blade 22, the branches44 are straightened according to the modification to be obtained. Themaximum length of the body 30 is obtained when the branches arerectilinear, as depicted in FIG. 2 a.

When the crank 26 is in its initial state, the branches 44 are notseparated to the maximum extent so that it is possible to separate themfurther in order to be able to reduce the length of the body 30 of thecrank 26.

By way of variant, not shown, the deformation of the branches 44 canconsist of an identical curvature of the two branches 44, which thenextend parallel with respect to each other.

One advantage stemming from the fact that the two ends 30 a, 30 b of thebody 30 of the crank 26 are brought together longitudinally, is that themodification of the angular travel “α” is symmetrical with respect toits bisecting line. Thus the adjustment of the angular position of thearm 22 with respect to the drive shaft 26 is independent of theadjustment of the angular travel “α”, each of these adjustment stepsbeing able thus to be performed without modifying the adjustmentobtained during the other step.

Such an adjustment step makes it possible to have immediate adjustmentof the angular travel “α” of each blade 22, without having to remove andthen refit any element of the wiper mechanism 20. This makes it possibleto eliminate any differences in adjustment due to a relative movement ofthe two pieces during refitting.

1. A method of adjusting the angular travel of a motor vehicle wipingmechanism (20), of the type comprising a link (24) and a crank (26), ofthe type in which the crank (26) comprises a body (30) which extendslongitudinally in a substantially horizontal plane, which is articulatedat a first end (30 a) about a vertical axis (A), which is articulated ata second end (30 b) on the link (24), of the type comprising a step ofadjusting the angular travel (α) by modifying the distance between thefirst and second articulated ends (30 a, 30 b) of the crank (26),characterised in that the adjustment step consists of modifying thelength of a longitudinal portion (40) of the body (30) of the crank(26).
 2. A method according to the preceding claim, characterised inthat the adjustment step consists of permanently deforming at least partof the longitudinal portion (40) of the body (30) of the crank (26). 3.A method according to any one of the preceding claims, characterised inthat the adjustment step consists of reducing the length of the portion(40) of the body (30) of the crank (26) by bringing together thearticulated ends (30 a, 30 b) of the body (30) of the crank (26) in alongitudinal direction.
 4. A method according to any one of thepreceding claims, characterised in that the adjustment step is performedafter a step of mounting the wiper mechanism (20) on a test bench.
 5. Acrank (26) belonging to a movement transmission linkage of a motorvehicle wiper mechanism (20), of the type comprising a body (30) whichextends longitudinally in a horizontal plane and which comprises a firstlongitudinal end (30 a) articulated on a link (24) of the linkage, and asecond longitudinal end (30 b) which is connected to a wiper arm (22)and which is articulated about a vertical axis (A), of the type in whichthe distance between the two articulated ends (30 a, 30 b) of the crank(26) is adjustable, characterised in that the body (30) of the crank(26) comprises at least one portion (40) which is able to be deformedpermanently in order to modify and adjust the distance between the twoarticulated ends (30 a, 30 b) of the crank (26).
 6. A crank (26)according to the preceding claim, characterised in that the said portion(40) of the body (30) of the crank (26) comprises at least one oblonghole (42) of longitudinal orientation overall, which delimits twoopposite deformable longitudinal branches (44).
 7. A crank (26)according to the preceding claim, characterised in that the branches(44) of the crank (26) are roughly symmetrical with respect to a medianlongitudinal axis of the crank (26).